Polymer functional group impact on the thermo-mechanical properties of polyacrylic acid, polyacrylic amide- poly (vinyl alcohol) nanocomposites reinforced by graphene oxide nanosheets

Impact of graphene oxide nanosheets and polymethyl methacrylate on nano/hybrid-based restoration dental filler composites: ultrasound behavior and antibacterial activity

PURPOSE

Graphene-polymer nanocomposites significantly impact dental filler and antibacterial applications. The study aims to overcome some problems dental filers present and improve their properties and antibacterial activity. Synthesis graphene oxide (GO) and poly (methyl methacrylate) (PMMA) were used to reinforce two types of commercial hybrid/nano-dental fillings.

METHODS

Developed acoustic-solution-sonication-casting methods were applied to fabricate the new graphene-polymer-dental filler nanocomposites. The structure, morphology, rheological and mechanical properties, and antibacterial of the newly fabricated filling-PMMA/ GO nanocomposites were investigated.

RESULTS

Fourier transform infrared (FTIR) showed a significant interaction between the filling and the additional materials. The X-ray diffraction (XRD) analysis revealed a considerable change in crystalline behavior. Optical microscope (OM) with field emission scanning electron microscopy (FESEM) pictures demonstrated a substantial change in the morphology of the samples with a homogeneous and fine dispersion of the nanomaterials in the filler matrix. Multi-frequency ultrasound mechanical properties measured the ultrasonic velocity, absorption coefficient, compressibility, bulk modulus, and other mechanical properties that notably enhanced after GO contributed up to 325% of the ultrasonic absorption coefficient compared with hybrid/nano-fillers. Rheological properties were measured as viscosity, absorption coefficient, and specific viscosity, which significantly improved after adding PMMA and incorporating GO up to 57% of the viscosity, compared with hybrid/nano-fillers. The inhibition zone of moth bacteria, such as Enterococcus faecalis and E. staph bacteria, improved after the contribution of GO nanosheets up to 46%.

CONCLUSION

Nanofillers nanocomposites presented better properties and inhabitances zone diameter of antibacterial.

Elastomeric Trilayer Substrates with Native-like Mechanical Properties for Heart Valve Leaflet Tissue Engineering

Heart valve leaflets have a complex trilayered structure with layer-specific orientations, anisotropic tensile properties, and elastomeric characteristics that are difficult to mimic collectively. Previously, trilayer leaflet substrates intended for heart valve tissue engineering were developed with nonelastomeric biomaterials that cannot deliver native-like mechanical properties. In this study, by electrospinning polycaprolactone (PCL) polymer and poly(l-lactide-co-ε-caprolactone) (PLCL) copolymer, we created elastomeric trilayer PCL/PLCL leaflet substrates with native-like tensile, flexural, and anisotropic properties and compared them with trilayer PCL leaflet substrates (as control) to find their effectiveness in heart valve leaflet tissue engineering. These substrates were seeded with porcine valvular interstitial cells (PVICs) and cultured for 1 month in static conditions to produce cell-cultured constructs. The PCL/PLCL substrates had lower crystallinity and hydrophobicity but higher anisotropy and flexibility than PCL leaflet substrates. These attributes contributed to more significant cell proliferation, infiltration, extracellular matrix production, and superior gene expression in the PCL/PLCL cell-cultured constructs than in the PCL cell-cultured constructs. Further, the PCL/PLCL constructs showed better resistance to calcification than PCL constructs. Trilayer PCL/PLCL leaflet substrates with native-like mechanical and flexural properties could significantly improve heart valve tissue engineering.

Effect of green synthesis bimetallic Ag@SiO2 core–shell nanoparticles on absorption behavior and electrical properties of PVA-PEO nanocomposites for optoelectronic applications

A green and easy technique was used to synthesize silver and silica (Ag@SiO2) core–shell nanoparticles (NPs) in the matrix blend polymers matrix. Core–shell nanoparticles were loaded into polyvinyl alcohol (PVA) and ultrahigh molecular weight polyethylene oxide (UHMW-PEO) blended polymer to fabricate new nanocomposite films (NCFs) using the developed solution-sonication-casting technique. The spectroscopic properties of the resultant films were investigated using x-ray diffraction (XRD), Fourier transforms infrared (FTIR), visible light microscope (OLM), field emission scanning electron microscope (FESEM), FESEM-energy dispersive spectroscope (FESM-EDX), UV/visible spectrometer, and LCR meter to investigate the structural, morphological, optical, and electrical characteristics. XRD revealed the presence of the semi-crystalline nature of PVA-UHMWPEO/ Ag@SiO2 NCFs. The degree of crystallinity increased after embedding. The NPs were well distributed within the NCFs according to OLM and SEM, and FESM-EDX confirmed the presence of C, O, Si, and Ag elements. FTIR spectrum observed strong bonding after the loading of NPs, and other peaks were hidden. The UV/visible spectrums suggested an absorption at ~ 210 nm. Based on the Tauc plot model, the optical bandgap (Eg) values decreased from 5.52 eV to 4.57 eV. The electrical conductivity values were significantly increased with the increasing frequency and (Ag@SiO2) core–shell nanoparticles (NPs) loading ratio. The PVA-UHMWPEO/Ag@SiO2 NCFs explained enhanced lattice strain. The obtained NCFs are suitable for use in various optoelectronic and nanodevice applications.